netapp/src/proto.rs

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use std::collections::{HashMap, VecDeque};
use std::pin::Pin;
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use std::sync::Arc;
use std::task::{Context, Poll};
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use log::{trace, warn};
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use futures::channel::mpsc::{unbounded, UnboundedReceiver, UnboundedSender};
use futures::Stream;
use futures::{AsyncReadExt, AsyncWriteExt, FutureExt, StreamExt};
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use kuska_handshake::async_std::BoxStreamWrite;
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use tokio::sync::mpsc;
use async_trait::async_trait;
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use crate::error::*;
use crate::util::AssociatedStream;
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/// Priority of a request (click to read more about priorities).
///
/// This priority value is used to priorize messages
/// in the send queue of the client, and their responses in the send queue of the
/// server. Lower values mean higher priority.
///
/// This mechanism is usefull for messages bigger than the maximum chunk size
/// (set at `0x4000` bytes), such as large file transfers.
/// In such case, all of the messages in the send queue with the highest priority
/// will take turns to send individual chunks, in a round-robin fashion.
/// Once all highest priority messages are sent successfully, the messages with
/// the next highest priority will begin being sent in the same way.
///
/// The same priority value is given to a request and to its associated response.
pub type RequestPriority = u8;
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/// Priority class: high
pub const PRIO_HIGH: RequestPriority = 0x20;
/// Priority class: normal
pub const PRIO_NORMAL: RequestPriority = 0x40;
/// Priority class: background
pub const PRIO_BACKGROUND: RequestPriority = 0x80;
/// Priority: primary among given class
pub const PRIO_PRIMARY: RequestPriority = 0x00;
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/// Priority: secondary among given class (ex: `PRIO_HIGH | PRIO_SECONDARY`)
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pub const PRIO_SECONDARY: RequestPriority = 0x01;
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// Messages are sent by chunks
// Chunk format:
// - u32 BE: request id (same for request and response)
// - u16 BE: chunk length, possibly with CHUNK_HAS_CONTINUATION flag
// when this is not the last chunk of the message
// - [u8; chunk_length] chunk data
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pub(crate) type RequestID = u32;
type ChunkLength = u16;
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const MAX_CHUNK_LENGTH: ChunkLength = 0x4000;
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const CHUNK_HAS_CONTINUATION: ChunkLength = 0x8000;
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struct SendQueueItem {
id: RequestID,
prio: RequestPriority,
data: DataReader,
}
pub(crate) enum Data {
Full(Vec<u8>),
Streaming(AssociatedStream),
}
#[pin_project::pin_project(project = DataReaderProj)]
enum DataReader {
Full {
#[pin]
data: Vec<u8>,
pos: usize,
},
Streaming {
#[pin]
reader: AssociatedStream,
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packet: Vec<u8>,
pos: usize,
buf: Vec<u8>,
eos: bool,
},
}
impl From<Data> for DataReader {
fn from(data: Data) -> DataReader {
match data {
Data::Full(data) => DataReader::Full { data, pos: 0 },
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Data::Streaming(reader) => DataReader::Streaming {
reader,
packet: Vec::new(),
pos: 0,
buf: Vec::with_capacity(MAX_CHUNK_LENGTH as usize),
eos: false,
},
}
}
}
impl Stream for DataReader {
type Item = ([u8; MAX_CHUNK_LENGTH as usize], usize);
fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<Self::Item>> {
match self.project() {
DataReaderProj::Full { data, pos } => {
let len = std::cmp::min(MAX_CHUNK_LENGTH as usize, data.len() - *pos);
let end = *pos + len;
if len == 0 {
Poll::Ready(None)
} else {
let mut body = [0; MAX_CHUNK_LENGTH as usize];
body[..len].copy_from_slice(&data[*pos..end]);
*pos = end;
Poll::Ready(Some((body, len)))
}
}
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DataReaderProj::Streaming {
mut reader,
packet,
pos,
buf,
eos,
} => {
if *eos {
// eos was reached at previous call to poll_next, where a partial packet
// was returned. Now return None
return Poll::Ready(None);
}
loop {
let packet_left = packet.len() - *pos;
let buf_left = MAX_CHUNK_LENGTH as usize - buf.len();
let to_read = std::cmp::min(buf_left, packet_left);
buf.extend_from_slice(&packet[*pos..*pos + to_read]);
*pos += to_read;
if buf.len() == MAX_CHUNK_LENGTH as usize {
// we have a full buf, ready to send
break;
}
// we don't have a full buf, packet is empty; try receive more
if let Some(p) = futures::ready!(reader.as_mut().poll_next(cx)) {
*packet = p;
*pos = 0;
} else {
*eos = true;
break;
}
}
let mut body = [0; MAX_CHUNK_LENGTH as usize];
let len = buf.len();
body[..len].copy_from_slice(buf);
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buf.clear();
Poll::Ready(Some((body, len)))
}
}
}
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}
struct SendQueue {
items: VecDeque<(u8, VecDeque<SendQueueItem>)>,
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}
impl SendQueue {
fn new() -> Self {
Self {
items: VecDeque::with_capacity(64),
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}
}
fn push(&mut self, item: SendQueueItem) {
let prio = item.prio;
let pos_prio = match self.items.binary_search_by(|(p, _)| p.cmp(&prio)) {
Ok(i) => i,
Err(i) => {
self.items.insert(i, (prio, VecDeque::new()));
i
}
};
self.items[pos_prio].1.push_back(item);
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}
fn pop(&mut self) -> Option<SendQueueItem> {
match self.items.pop_front() {
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None => None,
Some((prio, mut items_at_prio)) => {
let ret = items_at_prio.pop_front();
if !items_at_prio.is_empty() {
self.items.push_front((prio, items_at_prio));
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}
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ret.or_else(|| self.pop())
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}
}
}
fn is_empty(&self) -> bool {
self.items.iter().all(|(_k, v)| v.is_empty())
}
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}
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/// The SendLoop trait, which is implemented both by the client and the server
/// connection objects (ServerConna and ClientConn) adds a method `.send_loop()`
/// that takes a channel of messages to send and an asynchronous writer,
/// and sends messages from the channel to the async writer, putting them in a queue
/// before being sent and doing the round-robin sending strategy.
///
/// The `.send_loop()` exits when the sending end of the channel is closed,
/// or if there is an error at any time writing to the async writer.
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#[async_trait]
pub(crate) trait SendLoop: Sync {
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async fn send_loop<W>(
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self: Arc<Self>,
mut msg_recv: mpsc::UnboundedReceiver<(RequestID, RequestPriority, Data)>,
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mut write: BoxStreamWrite<W>,
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) -> Result<(), Error>
where
W: AsyncWriteExt + Unpin + Send + Sync,
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{
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let mut sending = SendQueue::new();
let mut should_exit = false;
while !should_exit || !sending.is_empty() {
if let Ok((id, prio, data)) = msg_recv.try_recv() {
match &data {
Data::Full(data) => {
trace!("send_loop: got {}, {} bytes", id, data.len());
}
Data::Streaming(_) => {
trace!("send_loop: got {}, unknown size", id);
}
}
sending.push(SendQueueItem {
id,
prio,
data: data.into(),
});
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} else if let Some(mut item) = sending.pop() {
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trace!("send_loop: sending bytes for {}", item.id,);
let data = futures::select! {
data = item.data.next().fuse() => data,
default => {
// nothing to send yet; re-schedule and find something else to do
sending.push(item);
continue;
// TODO if every SendQueueItem is waiting on data, use select_all to await
// something to do
}
};
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let header_id = RequestID::to_be_bytes(item.id);
write.write_all(&header_id[..]).await?;
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let data = match data.as_ref() {
Some((data, len)) => &data[..*len],
None => &[],
};
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if data.len() == MAX_CHUNK_LENGTH as usize {
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let size_header =
ChunkLength::to_be_bytes(data.len() as u16 | CHUNK_HAS_CONTINUATION);
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write.write_all(&size_header[..]).await?;
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write.write_all(data).await?;
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sending.push(item);
} else {
let size_header = ChunkLength::to_be_bytes(data.len() as u16);
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write.write_all(&size_header[..]).await?;
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write.write_all(data).await?;
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}
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write.flush().await?;
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} else {
let sth = msg_recv.recv().await;
if let Some((id, prio, data)) = sth {
match &data {
Data::Full(data) => {
trace!("send_loop: got {}, {} bytes", id, data.len());
}
Data::Streaming(_) => {
trace!("send_loop: got {}, unknown size", id);
}
}
sending.push(SendQueueItem {
id,
prio,
data: data.into(),
});
} else {
should_exit = true;
}
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}
}
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let _ = write.goodbye().await;
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Ok(())
}
}
struct ChannelPair {
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receiver: Option<UnboundedReceiver<Vec<u8>>>,
sender: Option<UnboundedSender<Vec<u8>>>,
}
impl ChannelPair {
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fn take_receiver(&mut self) -> Option<UnboundedReceiver<Vec<u8>>> {
self.receiver.take()
}
fn take_sender(&mut self) -> Option<UnboundedSender<Vec<u8>>> {
self.sender.take()
}
fn ref_sender(&mut self) -> Option<&UnboundedSender<Vec<u8>>> {
self.sender.as_ref().take()
}
fn insert_into(self, map: &mut HashMap<RequestID, ChannelPair>, index: RequestID) {
if self.receiver.is_some() || self.sender.is_some() {
map.insert(index, self);
}
}
}
impl Default for ChannelPair {
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fn default() -> Self {
let (send, recv) = unbounded();
ChannelPair {
receiver: Some(recv),
sender: Some(send),
}
}
}
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/// The RecvLoop trait, which is implemented both by the client and the server
/// connection objects (ServerConn and ClientConn) adds a method `.recv_loop()`
/// and a prototype of a handler for received messages `.recv_handler()` that
/// must be filled by implementors. `.recv_loop()` receives messages in a loop
/// according to the protocol defined above: chunks of message in progress of being
/// received are stored in a buffer, and when the last chunk of a message is received,
/// the full message is passed to the receive handler.
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#[async_trait]
pub(crate) trait RecvLoop: Sync + 'static {
fn recv_handler(self: &Arc<Self>, id: RequestID, msg: Vec<u8>, stream: AssociatedStream);
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async fn recv_loop<R>(self: Arc<Self>, mut read: R) -> Result<(), Error>
where
R: AsyncReadExt + Unpin + Send + Sync,
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{
let mut receiving: HashMap<RequestID, Vec<u8>> = HashMap::new();
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let mut streams: HashMap<RequestID, ChannelPair> = HashMap::new();
loop {
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trace!("recv_loop: reading packet");
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let mut header_id = [0u8; RequestID::BITS as usize / 8];
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match read.read_exact(&mut header_id[..]).await {
Ok(_) => (),
Err(e) if e.kind() == std::io::ErrorKind::UnexpectedEof => break,
Err(e) => return Err(e.into()),
};
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let id = RequestID::from_be_bytes(header_id);
trace!("recv_loop: got header id: {:04x}", id);
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let mut header_size = [0u8; ChunkLength::BITS as usize / 8];
read.read_exact(&mut header_size[..]).await?;
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let size = ChunkLength::from_be_bytes(header_size);
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trace!("recv_loop: got header size: {:04x}", size);
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let has_cont = (size & CHUNK_HAS_CONTINUATION) != 0;
let size = size & !CHUNK_HAS_CONTINUATION;
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let mut next_slice = vec![0; size as usize];
read.read_exact(&mut next_slice[..]).await?;
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trace!("recv_loop: read {} bytes", next_slice.len());
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if id & 1 == 0 {
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// main stream
let mut msg_bytes = receiving.remove(&id).unwrap_or_default();
msg_bytes.extend_from_slice(&next_slice[..]);
if has_cont {
receiving.insert(id, msg_bytes);
} else {
let mut channel_pair = streams.remove(&(id | 1)).unwrap_or_default();
if let Some(receiver) = channel_pair.take_receiver() {
self.recv_handler(id, msg_bytes, Box::pin(receiver));
} else {
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warn!("Couldn't take receiver part of stream")
}
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channel_pair.insert_into(&mut streams, id | 1);
}
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} else {
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// associated stream
let mut channel_pair = streams.remove(&(id)).unwrap_or_default();
// if we get an error, the receiving end is disconnected. We still need to
// reach eos before dropping this sender
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if !next_slice.is_empty() {
if let Some(sender) = channel_pair.ref_sender() {
let _ = sender.unbounded_send(next_slice);
} else {
warn!("Couldn't take sending part of stream")
}
}
if !has_cont {
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channel_pair.take_sender();
}
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channel_pair.insert_into(&mut streams, id);
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}
}
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Ok(())
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}
}
#[cfg(test)]
mod test {
use super::*;
#[test]
fn test_priority_queue() {
let i1 = SendQueueItem {
id: 1,
prio: PRIO_NORMAL,
data: DataReader::Full {
data: vec![],
pos: 0,
},
};
let i2 = SendQueueItem {
id: 2,
prio: PRIO_HIGH,
data: DataReader::Full {
data: vec![],
pos: 0,
},
};
let i2bis = SendQueueItem {
id: 20,
prio: PRIO_HIGH,
data: DataReader::Full {
data: vec![],
pos: 0,
},
};
let i3 = SendQueueItem {
id: 3,
prio: PRIO_HIGH | PRIO_SECONDARY,
data: DataReader::Full {
data: vec![],
pos: 0,
},
};
let i4 = SendQueueItem {
id: 4,
prio: PRIO_BACKGROUND | PRIO_SECONDARY,
data: DataReader::Full {
data: vec![],
pos: 0,
},
};
let i5 = SendQueueItem {
id: 5,
prio: PRIO_BACKGROUND | PRIO_PRIMARY,
data: DataReader::Full {
data: vec![],
pos: 0,
},
};
let mut q = SendQueue::new();
q.push(i1); // 1
let a = q.pop().unwrap(); // empty -> 1
assert_eq!(a.id, 1);
assert!(q.pop().is_none());
q.push(a); // 1
q.push(i2); // 2 1
q.push(i2bis); // [2 20] 1
let a = q.pop().unwrap(); // 20 1 -> 2
assert_eq!(a.id, 2);
let b = q.pop().unwrap(); // 1 -> 20
assert_eq!(b.id, 20);
let c = q.pop().unwrap(); // empty -> 1
assert_eq!(c.id, 1);
assert!(q.pop().is_none());
q.push(a); // 2
q.push(b); // [2 20]
q.push(c); // [2 20] 1
q.push(i3); // [2 20] 3 1
q.push(i4); // [2 20] 3 1 4
q.push(i5); // [2 20] 3 1 5 4
let a = q.pop().unwrap(); // 20 3 1 5 4 -> 2
assert_eq!(a.id, 2);
q.push(a); // [20 2] 3 1 5 4
let a = q.pop().unwrap(); // 2 3 1 5 4 -> 20
assert_eq!(a.id, 20);
let b = q.pop().unwrap(); // 3 1 5 4 -> 2
assert_eq!(b.id, 2);
q.push(b); // 2 3 1 5 4
let b = q.pop().unwrap(); // 3 1 5 4 -> 2
assert_eq!(b.id, 2);
let c = q.pop().unwrap(); // 1 5 4 -> 3
assert_eq!(c.id, 3);
q.push(b); // 2 1 5 4
let b = q.pop().unwrap(); // 1 5 4 -> 2
assert_eq!(b.id, 2);
let e = q.pop().unwrap(); // 5 4 -> 1
assert_eq!(e.id, 1);
let f = q.pop().unwrap(); // 4 -> 5
assert_eq!(f.id, 5);
let g = q.pop().unwrap(); // empty -> 4
assert_eq!(g.id, 4);
assert!(q.pop().is_none());
}
}